When a disaster has occurred, it is important to secure communications in various situations such as victim relief, evacuation guidance, operations of evacuation centers, restoration support, etc. In recent years, the spread of mobile terminals such as smart phones or tablet computers provided with the wireless LAN (Local Area Network) function has led to expectation that wireless LAN will be utilized as communications in a case of a disaster. For example, guidelines have been drawn up for opening free accesses to wireless LANs provided by business entities that usually provide public wireless LAN services, in a case of a large-scale disaster. Opening of wireless LANs not only by business entities but also by local governments or by companies in a case of a disaster is also being discussed.
Also, in recent years, attention has been focused on virtual networks using software and on Software Defined Networking (SDN), which is a technique used for forming a virtual network. According to SDN, the topology and QoS (Quality of Service) of a network are set by way of software. According to this technique, a control device called a controller in a network monitors communication states of devices included in the network so as to conduct control in accordance with the states of the respective devices. Note that the only information used by a controller for conducting the setting of a network topology etc. is the communication states of monitoring target devices in the network.
The documents below are known as documents about related arts.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2014-86881    [Non Patent Document 1] “Version 1.0 of Guideline for Emergency free Wi-Fi for the Large-Scale Disaster Relief” [online] Apr. 21, 2014, Wireless LAN Business Promotion Conference, the Internet <http://www.wlan-business.org/info/pdf/Wi-Fi_Free_Guideline_v1.01_20140527.pdf>
When a wireless LAN is opened in a case of a disaster, selection and a setting change are conducted for access points for accepting accesses that are made in response to the opening. Setting changes are conducted manually by the operator for each access point, leading to a situation where a large number of access points result in more complicated processes to be conducted by the operator and longer time for setting changes. Further, it is also difficult for the operator to select access points that are appropriate for the statuses of damages, the location of the disaster, etc.